Lead Alloy Grids
The present day standard battery grids are made from lead to which approximately 4% to 6% of antimony has been added as a stiffener since a pure lead grid would be quite soft and unmanageable in the conventional process of battery plate manufacture. The present grids for automotive batteries weigh about from 60 to 70 grams and the grids serve a dual purpose of being an electrical conductor and acting as a mechanical frame to hold lead oxide paste. When the grid is pasted it is then called a battery plate. Lead is used in the grids since it is relatively insoluble in sulfuric acid which serves as the electrolyte. Other metals that are good conductors such as copper are soluble in sulfuric acid and would poison a lead acid battery.
As is well known, the conventional battery grid generally comprises a rectangular frame formed with rectangular openings and a laterally projecting lug on its upper edge by means of which a plurality of grids of similar polarity may be fused together or electrically connected in parallel by a bar leading to a battery post.
Normally, the conventional battery grid having a substantially rectangular frame portion, is manufactured by covering the individual grids with a paste of lead oxide containing some sulfuric acid. These pasted grids are then dried and subjected to an electrical charge while in sulfuric acid whereby one group of plates called the negative plates have their lead oxide converted to lead and another group of plates called the positive plates have their lead oxide converted to lead peroxide. A series of such plates are then placed in a cell with alternating negative and positive plates positioned so that the end plates in each cell are negative. Insulated separators such as fluted wood, perforated rubber, glass fiber reinforced compositions and the like, are placed between each battery plate and the battery casing is then filled with a dilute solution of sulfuric acid.
The porous separators which are placed between the alternating negative and positive plates have the primary object of preventing metallic contact between the plates of opposite polarity while freely permitting electrolytic conduction.
A cell comprises a number of plates, the positive plates being connected in parallel with each other and the negative plates being connected in parallel with each other so that the entire cell has a desired amperage and a voltage of approximately 2.1 volts. Depending on the desired voltage of the battery, the requisite number of cells are then connected in series, for example, six cells connected in series to provide a 12 volt battery.